This invention relates to diving snorkels (referred to hereinafter simply as "snorkel" or "snorkels") allowing a diver to breathe as the diver swims under water.
Typical known snorkels generally comprise a ventilating portion including an air inlet, a mouthpiece, a draining portion having a non-return valve, and a main pipe connecting these air inlet, mouthpiece and draining portions, said ventilating portion being positioned above the water surface while the mouthpiece and the draining portion are positioned below the water surface during use of the snorkel. Once a diver has surfaced and the air inlet of the snorkel has been exposed above the water surface, water which has entered the snorkel is partially expelled out from the non-return valve under the effect of a differential water pressure until the water level within the snorkel comes down to the water surface. The non-return valve is adapted to be normally opened downward with respect to the water surface. The diver may intensely breathe out through the mouthpiece to expel out the rest of the water still remaining within the snorkel from the draining portion and the air inlet. Arrangements of such known snorkels are disclosed, for example, in Japanese Utility Model Application disclosure Gazette No. 1974-33039 and U.S. Pat. No. 4,278,080.
When the snorkel is washed by a wave during its use, free breathing by a diver is sometimes hindered by a quantity of water flowing into the snorkel through the air inlet. While any quantity of water flowing into a conventional snorkel can be expelled outwardly therefrom by intense exhalation by the diver, it has been difficult for the conventional snorkel to prevent water from flowing into the snorkel. To solve this problem, various improvements have been proposed. For example, U.S. Pat. No. 4,879,995 discloses an arrangement comprising a first pipe having an air inlet and a second pipe having a mouthpiece wherein the first pipe has a flared end provided with a non-return valve and the second pipe is connected substantially in series with said flared end of the first pipe. This arrangement allows a quantity of water that has flowed into the snorkel to be drained out through the non-return valve with no portion of said quantity reaching the mouthpiece. However, said flared end has a construction which is complicated, resulting in that both the assembly and maintenance of such a snorkel is a time-consuming job.
Accordingly, it is a principal object of the present invention to effectively inhibit the flow of water which otherwise might enter the main pipe by providing a relatively simple arrangement such that an assembly of first and second pipe portions extending in parallel to each other and communicating with each other is connected to the upper end of the snorkel's main pipe, wherein the wall of the second pipe portion serves as a dam adapted to inhibit the flow of water into the main pipe through a communication port provided between said first and second pipe portions.
The object set forth above can be achieved, according to one embodiment of the invention, by a diving snorkel comprising a ventilating portion provided with an air inlet adapted to be positioned above the water surface, a mouthpiece being positioned below the water surface a draining portion being provided with a first non-return valve adapted to be normally opened downward respect to the water surface, during use of the snorkel, and a main pipe connecting said air inlet with said mouthpiece and said draining portion, wherein said ventilating portion comprises a first pipe portion and a second pipe portion extending in parallel to each other and a communicating port provided to establish communication between these two pipe portions; wherein the first pipe portion has an upper end defined by a top wall and a lower end connected integrally with the main pipe; wherein the second pipe portion has an upper end defined by the air inlet and a lower end having an outlet that will permit the downward drainage of water through the second pipe portion; and wherein the port is provided between the air inlet and said outlet.
Preferably, the first pipe portion and the second pipe portion have a common inner wall separating these two pipe portions and the communicating port is at least partially defined in the first pipe portion by said common inner wall and the top wall.
With the snorkel constructed as described above, a side wall of the second pipe portion extends in front of the communicating port so as to at least partially conceal the port and functions as a dam or a barrier serving to obstruct the flow of water which otherwise might enter the main pipe through the communicating port. Even when the snorkel is washed by wave, the quantity of water flowing into the second pipe portion can be drained out through a non-return valve provided in the lower end of the second pipe portion.